Hitherto, a manufacturing method of semiconductor devices or the like includes a plurality of steps of processes, during each of which gas systems introduced into a chamber are varied in order to enable continuous processing such as multi-layered film processing using a reactive ion etching (RIE) process. In general, a mass flow controller is used to adjust a flow rate of a gas introduced into the chamber.
However, the existing mass flow controller generally performs feed-back control of comparing a flow rate detected by a flow rate detector with a flow rate setting value and adjusting an opening degree of a valve in accordance with the difference therebetween. For this reason, for example, when the flow rate of the gas needs to be changed, there is a problem in that it takes a time for the opening of the valve to reach a desired degree which results in a desired flow rate, after a flow rate setting value is changed.